There is previously known a fastener, in which cam parts to contact with each other are provided respectively on a female fastener and a male fastener (see: Patent Document 1, page 4, left column, lines 4 to 8; same page, left column, last line to same page, right column line 3; and FIG. 1).
The cam part of the above female fastener of the past is provided rising in an inclined form (see: Patent Document 1, page 4, left column, lines 7 to 8; and FIG. 1).